Heat exchangers have been developed for various devices, such as engine systems, computer systems, HVAC systems, and more. The heat exchangers are configured for directing heat within the device to components where such heat is beneficial to its operating performance, for directing heat away from components that normally cannot tolerate high temperatures, and/or where system operational constraints require controlled temperatures.
For example, gas turbine engines may include various heat exchangers. In one example, a class of heat exchangers known as recuperators have been developed to recover heat from the engine exhaust, which is otherwise wasted energy, and redirect the recovered engine exhaust heat to the pre-combustion portion of the engine, to increase its overall engine efficiency. Specifically, the recuperator is a heat exchanger that transfers some of the waste heat in the exhaust to the compressed air before it enters the combustion portion of the engine, thereby preheating it before entering the fuel combustor stage. Since the compressed air has been pre-heated, less fuel is needed to heat the compressed air/fuel mixture up to the desired turbine inlet temperature. By recovering some of the energy usually lost as waste heat, the recuperator can make a gas turbine engine significantly more efficient.
In another example, cooling air may be provided to various turbine engine components using cooling air extracted from other parts of the engine. More specifically, in some gas turbine engines, cooling air is extracted from the discharge of the compressor, and is then directed to certain portions of the turbine. During some operating conditions, the air that is extracted from the engine for cooling may be at temperatures that require the air to be cooled before being directed to the particular component requiring cooling. To achieve the required cooling, cooling air may be directed through one or more heat exchangers within the engine.
Conventional heat exchangers may be too heavy, bulky, and/or may not provide acceptable performance characteristics. Other heat exchangers may be too expensive and/or difficult to manufacture. Moreover, some heat exchangers may be susceptible to thermo- mechanical fatigue, which reduces their service life and/or necessitates costly repairs or replacement.
Hence, there is a need for improved heat exchangers for use in gas turbine engines and other applications having improved efficiency, reduced manufacturing costs, and increased operating lifespan. The present disclosure addresses at least these needs.